Superimposed hepatitis and the effect on viral replication in chronic hepatitis B

Recurrence of hepatitis D (delta) in liver transplants: histopathological aspects

BACKGROUND

The viral/pathological correlates of recurrent hepatitis delta virus (HDV) disease in orthotoptic liver transplants are reported.

METHODS

We examined the histological features of recurrent HDV disease in nine patients with transplants for terminal HDV cirrhosis were examined; intrahepatic HDV and hepatitis B virus (HBV) antigens were detected by immunoperoxidase techniques. Sera were tested for the battery of HDV and HBV markers.

RESULTS

In four patients, HDV reinfection was accompanied by the recurrence of an HBV infection with features of active viral replication. In the other five, HDV reinfection was accompanied by an atypical recurrence of HBV infection without evidence of active HBV replication (no expression of intrahepatic hepatitis B core antigen). In four of the latter patients, the atypical HBV pattern changed during the follow-up into a pattern of active viral replication accompanied by chronic necroinflammation detected during histology.

CONCLUSION

The pattern of recurrent HBV infection can influence the pathological aspects of the relapses of HDV disease in liver grafts.

Clinical types of HBsAg-positive hepatitis

Hepatitis B is a parenterally and sexually transmitted disease of global importance. It associates with hepatitis D in a consistent proportion of cases. The disease most frequently runs a subclinical and anicteric course, with a significant number of cases that become chronic. Chronic hepatitis may progress to cirrhosis or cancer. The strategies by which hepatitis B and hepatitis D can be diminished and eventually eliminated are: immunization, measures to prevent exposure to infective blood or blood derivatives and education (in particular awareness that hepatitis B is a sexually transmitted disease).

Co-expression of markers for hepatitis delta and hepatitis B viruses in human liver

Delta hepatitis (HDV) infection can only occur in the presence of hepatitis B (HBV) infection, as HDV requires a coat of HBV surface antigen (HBsAg) for assembly of complete virus. A number of studies have examined the variation of HBV markers in serum and liver during establishment of HDV infection, but none has systematically examined the relationship between the two viruses in individual hepatocytes. Liver biopsies from five patients with HDV/HBV infection were stained for HBsAg, HBV core antigen (HBcAg) and hepatitis D (delta) antigen (HDAg). Double immunostaining was performed with a combination of indirect immunoperoxidase and alkaline phosphatase/antialkaline phosphatase techniques. HDV and HBV antigens were expressed in all five liver biopsies. Co-localization of HBsAg was seen in up to 39% of HDAg positive cells, and HBcAg in up to 8% of HDAg positive cells. HBcAg was detectable in approximately 9% of HBsAg positive cells, and HBsAg in approximately 12% of HBcAg positive cells. HDV can replicate without HBV but ultimately requires HBV to produce complete virus and subsequently infect other cells. In this study the majority of HDV positive cells did not appear to contain HBV markers. This might suggest delta virus replication without assembly, or possibly sequential production/assembly of the virus.

Smouldering hepatitis B virus replication in patients with chronic liver disease and hepatitis delta virus superinfection

Hepatitis B virus deoxyribonucleic acid (HBV-DNA) was studied by Southern blot analysis in liver biopsy specimens from 75 HBsAg-positive patients with chronic liver disease living in southern Italy. Twenty-seven of the patients were hepatitis delta virus (HDV) superinfected. Intrahepatic HBV-DNA was detected in 54 (72%) patients, 32 (59%) of them with replicative forms. The presence of replicative forms was directly related to liver HBcAg and inversely related to liver HDAg, as shown by multivariate analysis. However, 14 patients with intrahepatic HBV-DNA non-replicative pattern and about half of HDV-infected patients were liver HBcAg and/or serum HBV-DNA positive, mostly in low amounts. Histological inflammatory activity was strongly related to liver HBcAg expression regardless of HDV superinfection, as confirmed by multivariate analysis. Our results confirm previous studies about the concordance between intrahepatic HBV-DNA replicative pattern and liver HBcAg expression and about inhibition by HDV of high-level HBV replication. However, they suggest that low-level HBV replication may have an important role in causing liver damage also among HDV-infected patients, in a population where the spreading of HBV and HDV is a naturally occurring event.

Serological diagnosis of hepatitis B and delta virus (HBV/HDV) coinfection

Diagnosis of acute hepatitis B virus/hepatitis delta virus (HBV/HDV) coinfection is currently based on detection of anti-HD, however this antibody may be undetectable during the acute phase of hepatitis. To evaluate the entity of misdiagnosis of HBV/HDV coinfection in acute HBsAg-anti-HBc IgM positive hepatitis we examined sera from 245 consecutive patients obtained at admission and day 30, 60, 120, 210 and 400 of their follow-up. Anti-HD was detected in the serum of 26 out of 245 patients (10.6%). In 15% of cases it was present at admission, while in 92% it was found after 30 days. The combined detection of HDV-RNA, HDAg and IgM anti-HD in acute phase sera allowed a correct etiologic diagnosis in 69% of the cases. These findings suggest that the prevalence of HBV/HDV coinfection is underestimated when anti-HD is the only marker to be detected during the acute phase of disease. A correct etiologic diagnosis can only be made by testing acute phase sera for all the available markers of HDV. However, the best cost-effective procedure is to test any patient with HBV markers at presentation for anti-HD, 30-40 days after the onset of symptoms.

Hepatitis delta virus as a global health problem

As a defective virus requiring helper functions of the hepatitis B virus (HBV), the hepatitis delta virus (HDV) develops only in patients with hepatitis B surface antigen (HBsAg); its presence aggravates the course of the underlying HBV infection. There is no specific prophylaxis against HDV, and its inactivation kinetics by physical and chemical agents are largely unknown. Thus, prevention of HDV in the HBsAg carrier at risk of superinfection is limited to environmental and barrier measures only. As normal persons are efficiently protected from HDV by hepatitis B vaccination, the risk of HDV is another indication for hepatitis B vaccination of at-risk individuals.

Immuno-light and electron microscopic features of chronic hepatitis D

A morphologic study with immunohistochemical detection of the viral antigens of hepatitis B and Delta was performed on 36 liver specimens from patients with delta positive chronic viral hepatitis B. Electron microscopy was performed in 9 cases. No light microscopic or ultrastructural features specific for hepatitis D were observed. Lymphocytic infiltration occurred more often close to hepatocytes containing either hepatitis Delta antigen or hepatitis B core antigen in the cytoplasm, suggesting an involvement of cellular immune mechanisms in chronic hepatitis D as well as in hepatitis B. The simultaneous expression of both HBcAg and Delta antigen in occasional specimens over longer time periods indicates the possible co-existence of both viruses without mutual inhibition.

Serological and histological follow up of chronic hepatitis B infection

In order to study the clinical, serological, and morphological evolution of chronic hepatitis B virus infection in childhood, a prospective study has been carried out. A total of 90 children with a chronic infection were followed up for a mean (SD) of 3 (1.8) years. At the beginning of the study, 61 children were asymptomatic and 77 were household contacts of chronic carriers. Serologically 77 were hepatitis B e antigen (HBeAg) positive and 71 of them were positive to hepatitis B virus DNA. The mean alanine aminotransferase activities were higher among HBeAg positive patients than in antihepatitis B e (anti-HBe) positive ones. The most severe histological damage was also found among HBeAg positive patients. The annual seroconversion rate was 14%. A significant increase in the alanine aminotransferase activity was observed 13 (5.6) months before appearance of anti-HBe in the 85% of cases. Among anti-HBe positive patients, the alanine aminotransferase activities were normal in all except three (19%), two of whom had intrahepatic delta antigen. An increase in the histological activity was observed among patients who maintained HBeAg presence while an amelioration of liver damage was observed in anti-HBe carriers.

Delta and non-A, non-B hepatitis viruses

A review is given on the current knowledge of the hepatitis delta virus (HDV), the only hepatotropic non-A and non-B (NANB) virus characterized, although the infection it causes requires infection with hepatitis B virus (HBV). Studies in chimpanzees have provided the most data now available on the putative NANB agents. Histologic and electron microscopic changes occurring in HDV and NANB hepatitis have been shown to be comparable, and some biologic, epidemiologic and clinical features are similar. However, the lack of cross-protection between NANB and HDV hepatitis in cross-challenge transmission experiments and the lack of hybridization between HDV-RNA and nucleic acids from NANB material indicate that HDV and the putative NANB agents are minimally, if at all, related.